3 Reasons Why Your Air Conditioner is Freezing Up

By | December 22, 2022

Three Reasons Why Your Air Conditioner Can Freeze Up
All air conditioners can freeze up when not operating correctly.

This includes almost any unit, from a big home unit to a small window-mounted unit.

Below we give the three of the most common reasons a unit can ice over and stop working.
 
3 Reasons Why an Air Conditioner Can Freeze Up

  1. Bad Air Flow
  2. All A/C units need to cycle air, or they will not work correctly.

    This means pulling air into a unit, usually through what is called Return Air, and then blowing the air back into a home, usually through vents.

    If air becomes blocked at the return air, such as a dirty filter, air will stop blowing, making a unit not operate as it is designed to do.

    Replacing a dirty air filter is a simple DIY job that needs to be done every so often to keep a unit operating correctly.

    Blocked vents, especially floor vents, also can happen and should be cleared so air can blow into a space.

  3. Low on Refrigerant
  4. A unit that is low on Refrigerant can also freeze up.

    While adding more Refrigerant is needed, most often, a leak is in the unit somewhere that will need to be found and sealed.

    Finding a leak, sealing it, and adding Refrigerant into a unit is best left to professionals.

    There are electronic leak detectors that can sniff out a leak, or in some cases, soap can be used on a suspected leak to find a bad spot.

    All units have a set amount of Refrigerant that can go into a unit before it does not work correctly, which a professional should be called to do.

    Refrigerant is sold by the pound and is filled into a unit by the pound ounces also.

  5. Setting Thermostat Too Low
  6. Most systems can run and cool down to about 15-20 degrees Celsius, 60-67 degrees Fahrenheit.

    Setting a unit colder than it is supposed to be set can make it ice over, much like a refrigerator freezer.

    Since an air conditioner is not meant to freeze but cool air, if set too low, it can sometimes freeze up.

    Setting a unit to a very low temperature will not cool a space up quicker, and depending on other variables, such as outside temperature, it can, at times, freeze a unit up.

How Do I Fix My Air Conditioner from Freezing Up?

Check the air filter to be sure it is not dirty and blocking the airflow.

When the airflow is blocked, the air conditioner can not work properly and may freeze up.

Also, check the vents are not blocked and air flows freely from them.

If the air filter is good and no vents are blocked, the system will need to be troubleshot by an HVAC technician to find the cause.

Will a Frozen Air Conditioner Fix Itself?

No, usually, a frozen air conditioner has a problem that needs to be fixed.

If the unit sits for a period of time and the ice melts away, it may work again for a short time and then freeze again.

The cause will need to be found why the unit is freezing up.

Category: HVAC how to

About Aaron H. Benetti

Aaron H. Benetti has worked in the HVAC field since 1991. He began his career as an HVAC installer and later began doing troubleshooting and repairs. Around 2010, he began to write books on HVAC topics, mainly tutorials and how-to information. Currently, Aaron writes many articles and posts for websites as well as books and videos on HVAC topics.

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